<?php
/**
 * CodeIgniter
 *
 * An open source application development framework for PHP
 *
 * This content is released under the MIT License (MIT)
 *
 * Copyright (c) 2014 - 2015, British Columbia Institute of Technology
 *
 * Permission is hereby granted, free of charge, to any person obtaining a copy
 * of this software and associated documentation files (the "Software"), to deal
 * in the Software without restriction, including without limitation the rights
 * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
 * copies of the Software, and to permit persons to whom the Software is
 * furnished to do so, subject to the following conditions:
 *
 * The above copyright notice and this permission notice shall be included in
 * all copies or substantial portions of the Software.
 *
 * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
 * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
 * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
 * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
 * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
 * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
 * THE SOFTWARE.
 *
 * @package    CodeIgniter
 * @author    EllisLab Dev Team
 * @copyright    Copyright (c) 2008 - 2014, EllisLab, Inc. (http://ellislab.com/)
 * @copyright    Copyright (c) 2014 - 2015, British Columbia Institute of Technology (http://bcit.ca/)
 * @license    http://opensource.org/licenses/MIT    MIT License
 * @link    http://codeigniter.com
 * @since    Version 3.0.0
 * @filesource
 */
defined('BASEPATH') OR exit('No direct script access allowed');

/**
 * PDO IBM DB2 Database Adapter Class
 *
 * Note: _DB is an extender class that the app controller
 * creates dynamically based on whether the query builder
 * class is being used or not.
 *
 * @package        CodeIgniter
 * @subpackage    Drivers
 * @category    Database
 * @author        EllisLab Dev Team
 * @link        http://codeigniter.com/user_guide/database/
 */
class CI_DB_pdo_ibm_driver extends CI_DB_pdo_driver {

    /**
     * Sub-driver
     *
     * @var    string
     */
    public $subdriver = 'ibm';

    // --------------------------------------------------------------------

    /**
     * Class constructor
     *
     * Builds the DSN if not already set.
     *
     * @param    array    $params
     * @return    void
     */
    public function __construct($params)
    {
        parent::__construct($params);

        if (empty($this->dsn))
        {
            $this->dsn = 'ibm:';

            // Pre-defined DSN
            if (empty($this->hostname) && empty($this->HOSTNAME) && empty($this->port) && empty($this->PORT))
            {
                if (isset($this->DSN))
                {
                    $this->dsn .= 'DSN='.$this->DSN;
                }
                elseif ( ! empty($this->database))
                {
                    $this->dsn .= 'DSN='.$this->database;
                }

                return;
            }

            $this->dsn .= 'DRIVER='.(isset($this->DRIVER) ? '{'.$this->DRIVER.'}' : '{IBM DB2 ODBC DRIVER}').';';

            if (isset($this->DATABASE))
            {
                $this->dsn .= 'DATABASE='.$this->DATABASE.';';
            }
            elseif ( ! empty($this->database))
            {
                $this->dsn .= 'DATABASE='.$this->database.';';
            }

            if (isset($this->HOSTNAME))
            {
                $this->dsn .= 'HOSTNAME='.$this->HOSTNAME.';';
            }
            else
            {
                $this->dsn .= 'HOSTNAME='.(empty($this->hostname) ? '127.0.0.1;' : $this->hostname.';');
            }

            if (isset($this->PORT))
            {
                $this->dsn .= 'PORT='.$this->port.';';
            }
            elseif ( ! empty($this->port))
            {
                $this->dsn .= ';PORT='.$this->port.';';
            }

            $this->dsn .= 'PROTOCOL='.(isset($this->PROTOCOL) ? $this->PROTOCOL.';' : 'TCPIP;');
        }
    }

    // --------------------------------------------------------------------

    /**
     * Show table query
     *
     * Generates a platform-specific query string so that the table names can be fetched
     *
     * @param    bool    $prefix_limit
     * @return    string
     */
    protected function _list_tables($prefix_limit = FALSE)
    {
        $sql = 'SELECT "tabname" FROM "syscat"."tables"
            WHERE "type" = \'T\' AND LOWER("tabschema") = '.$this->escape(strtolower($this->database));

        if ($prefix_limit === TRUE && $this->dbprefix !== '')
        {
            $sql .= ' AND "tabname" LIKE \''.$this->escape_like_str($this->dbprefix)."%' "
                .sprintf($this->_like_escape_str, $this->_like_escape_chr);
        }

        return $sql;
    }

    // --------------------------------------------------------------------

    /**
     * Show column query
     *
     * Generates a platform-specific query string so that the column names can be fetched
     *
     * @param    string    $table
     * @return    array
     */
    protected function _list_columns($table = '')
    {
        return 'SELECT "colname" FROM "syscat"."columns"
            WHERE LOWER("tabschema") = '.$this->escape(strtolower($this->database)).'
                AND LOWER("tabname") = '.$this->escape(strtolower($table));
    }

    // --------------------------------------------------------------------

    /**
     * Returns an object with field data
     *
     * @param    string    $table
     * @return    array
     */
    public function field_data($table)
    {
        $sql = 'SELECT "colname" AS "name", "typename" AS "type", "default" AS "default", "length" AS "max_length",
                CASE "keyseq" WHEN NULL THEN 0 ELSE 1 END AS "primary_key"
            FROM "syscat"."columns"
            WHERE LOWER("tabschema") = '.$this->escape(strtolower($this->database)).'
                AND LOWER("tabname") = '.$this->escape(strtolower($table)).'
            ORDER BY "colno"';

        return (($query = $this->query($sql)) !== FALSE)
            ? $query->result_object()
            : FALSE;
    }

    // --------------------------------------------------------------------

    /**
     * Update statement
     *
     * Generates a platform-specific update string from the supplied data
     *
     * @param    string    $table
     * @param    array    $values
     * @return    string
     */
    protected function _update($table, $values)
    {
        $this->qb_limit = FALSE;
        $this->qb_orderby = array();
        return parent::_update($table, $values);
    }

    // --------------------------------------------------------------------

    /**
     * Delete statement
     *
     * Generates a platform-specific delete string from the supplied data
     *
     * @param    string    $table
     * @return    string
     */
    protected function _delete($table)
    {
        $this->qb_limit = FALSE;
        return parent::_delete($table);
    }

    // --------------------------------------------------------------------

    /**
     * LIMIT
     *
     * Generates a platform-specific LIMIT clause
     *
     * @param    string    $sql    SQL Query
     * @return    string
     */
    protected function _limit($sql)
    {
        $sql .= ' FETCH FIRST '.($this->qb_limit + $this->qb_offset).' ROWS ONLY';

        return ($this->qb_offset)
            ? 'SELECT * FROM ('.$sql.') WHERE rownum > '.$this->qb_offset
            : $sql;
    }

}
